Resistance-bar



PATENTED SEPT. 20, 1904.

R. SCOTT. RESISTANCE BAR.

APPLICATION FILED MAY 28 1904 N0 MODEL.

iamsliwm mm INVENTOR 79 5J7.-

WITNESSES UNITED STATES Patented September 20, 1904.

PATENT OEEicE.

RESISTANCE-BAR.

SPECIFICATION forming part of Letters Patent No. 770,660, dated September 20, 1904. Application filed May 28, 1904:. Serial No. 210,313. (No model.)

To all whmn it 7771(07/ concern.-

Be it known that l, RALPH Soon. a citizen of the United States, residing at Vilkesbarre, in the county of Luzerne and State of Pennsylvania, have invented a new and useful Resistance-Bar, of which the following is a specification.

This invention relates to improvements in resistance devices, its principal object being to construct a resistance device of a character more simple and at the same time more effective than that in ordinary use. A further object of the invention is to provide a device of this character having a protective casing so arranged as to permit of expansion and contraction under varying degrees of temperature without danger of injury to either the resistance material or to the casing.

A still further object of the invention is to provide a novel, compact, and non-metallic resistance which may be used as a rheostat and employed for various purposes, such as in lighting or motor circuits.

With these and other objects in view, as will more fully hereinafter appear, the invention consists in the novel construction and arrangement of parts hereinafter fully described, illustrated in the accompanying drawings, and particularly pointed out in the appended claims, it being understood that various changes in the form, proportions, size, and minor details of the structure may be made without departing from the spirit or sacrificing any of the advantages of the invention.

In the accompanying drawings, Figure 1 is an elevation of a resistance bar or rod constructed in accordance with the invention, the protective casing being shown in section. Fig. 2 is a detail sectional view of one end of the resistance-bar, showing the manner of making the electrical connections therewith. Fig. 3 is an elevation of a resistance-bar provided with a plurality of contacts in order that it may be used in a rheostat. Fig. i is a transverse sectional elevation of the same. Fig. 5 is an elevation of a slightly-modified construction of the device illustrating the mounting of the movable contact, which may engage the contact at any point in the length of the resistance-bar. Fig. 6 is an elevation showing the variable resistance arranged in arcuate form.

Similar numerals of reference are employed to indicate corresponding parts throughout the several figures of the drawings.

The resistance element 10 is in the form of a rod of any length and of any shape in crosssection, preferably circular, and is made of non-metallic material, such as carbon, carbon compounds, or the like. At each end of the bar or rod is an axially-arranged threaded orifice 7, into which enters a threaded pin 4, that also screws into a threaded opening in a washer 0r collar 5, that is embedded in the material during the process of manufacture, and on the screw is also arranged a threaded washer 8, which is screwed up firmly against the end of the bar and serves to clamp the material between the washers 5 and 8 to insure perfect electrical contact. On the projecting portion of the threaded pin 4; is arranged a grooved washer 3, formed of insulating material, preferably of a heat-resisting material, such as mica, and the outer end of the pin serves as a binding-post 2, having an opening for the passage of a conducting-wire. and is provided with the usual wire-binding screw. I

The resistance-bar is surrounded by a protective casing 1, cylindrical in form and having an inturned end portion fitting into the groove of one of the insulating-washers 3, and the groove of the opposite washer receives a cap-piece 26, that extends within the opposite end of the protective casing to an extent sufficient to permit of a considerable range of movement of the resistance-bar as it expands and contracts under varying degrees of term perature. The protective casing 1 is provided with a number of perforations 9, through which air may freely circulate in order to cool the resistance-bar.

In Figs. 3 and 4 is illustrated a slight modification of the resistance-bar where high resistance or a certain number of steps are required. The resistance-bar 10 is constructed in the same manner as indicated in Fig. 1 and is provided with any desired number of collars 16, formed of metal and preferably placed upon the rod or bar during the process of manufacturing the latter. In order to insure perfect electrical contact between the metallic collar and the rod 10, screws 12 are tapped into the collar, and the rod and these screws may serve also as binding-posts for the electrical conductor. The number of collars may be increased or diminished in accordance with the number of steps required.

Fig. 5 illustrates a variable resistance in the form of a bar of non-metallic material, to which are secured a number of buttons or disks 15, the buttons being held in position in any suitable manner, as by molding them in the bar while the latter is being made. Over the bar extends a metallic frame 23, that is secured to a base-plate 20 and is slotted for almost its entire length in order to expose the contactbuttons 15. In the base-plate 20 are arranged binding-posts 21, that are connected one to the slotted bar 23 and the other to the end of the resistance bar or rod, connection in the latter case being preferably made through a bracket 25, that acts as a support for the resistance-bar. On the slotted bar 23 is mounted a slidable contact 19, having an operatingknob or handle 18, by which it may be moved for the full length of the bar, said contact-block being moved into engagement with any one of the contact-buttons 15 in order to vary the resistance in the circuit.

In Fig. 6 is illustrated a slight modification of the resistance-bar, the latter in this instance being arcuate in form and provided with contacts of any desired character ar ranged at intervals throughout its length. In the present instance these contacts are shown in the form of buttons 15, which may be engaged by a contact-block 19', carrying a pivotally-mounted arm and provided with an operating knob or handle 18, by means of which the contact may be moved into engagement with any one of the contacts or buttons carried by the arcuate bar.

The device forming the subject of the present invention forms an economical and convenient substitute for the resistance-coil in similar resistance devices in ordinary use and being compact may be employed and manufactured where it is impossible to satisfactoril y connect resistance-coils of the usual type.

Having thus described the invention, what is claimed is- 1. A non-metallic resistance-bar, a plurality of spaced metallic bands encircling said bar, and band-securing devices having their ends embedded in material of which the bar is formed.

2. A resistance-bar, and a two-part telescopic casing surrounding the same and provided with air-circulating openings, the two parts of the casing being supported respectively by the opposite ends of the resistancebar.

3. Aresistance-bar formed of non-metallic material having threaded end portions, a threaded washer inserted in each of them, a threaded pin screwed into the washer and bar, an auxiliary clamping-washer also carried by the pin and in contact with the end of the bar, a grooved washer of insulating material mounted on the pin, a binding-post carried by said pin, and a two-part telescopic casing of which the members are supported by said grooved washers.

4. A resistance-bar formed of non-metallic material and provided with a plurality of spaced contacts, a slotted metallic bar arranged parallel with the resistance-bar, and a slidable contact carried by said slotted bar.

5. A resistance-bar formed of non-metallic material and provided with a plurality of spaced contacts, a slotted metallic bar arranged parallel with the resistance-bar, a contact-block carried by the slotted bar, and a handled operating member secured to said contact-block.

In testimony that I claim the foregoing as my own I have hereto affixed my signature in the presence of two witnesses. w.-

RALPH SCOTT.

Witnesses:

FRANK SCOTT, J. F. ONEILL. 

